Invasion by alien species represents one of the greatest biological threats to biodiversity, second only to habitat destruction. In addition to affecting ecosystems and contributing to the extinction of native species, invasive alien species also cause major socio-economic damage. The European Union has no specific legislation on invasive alien species, but a number of regulations and directives include provisions to deal directly or indirectly with IAS.
The most important are the Birds and Habitats directives, and the wildlife trade regulation. The problem of alien species has had tackled within many Natura 2000 sites, the EU network of protected areas aimed at protecting and conserving wild species of flora and fauna, and natural and semi natural habitats considered of Community importance. From 1992 to 2002, out of a total of 715 projects financed through the LIFE Nature program, the financial instrument aimed at the development of the Natura 2000 network, more than 100 include actions dealing with the management of exotic species.